Adapter



Oct. 26, 1965 w. R. WORKMAN 3,214,583

ADAPTER Filed Jan. 22, 1962 5)/ WEJLEY WOP/(MAN A77 NE 5 United States Patent Oli" 3,Zl4,583 Patented ct. 26, 1965 3,214,5ss ADAPTER Wesley R. Workman, St. Paul, Minn., assigner to Minnesota Mining and Manufacturing Company, St. Pani, Minn., a corporation of Delaware raies ran. 22, 1962, ser. No. 167,561 3 Claims. (Cl. Z50-65) This invention relates to the heat-lamination of paperlike sheet materials, and has particular reference to the heat-laminating of thermographic copy sheets to adhesivecoated reinforcing back-up sheets utilizing thermographic copy-machines to provide the activating heat energy, and to auxiliary apparatus useful for this and other applications.

One well-known and commercially important method of making copies of typewritten correspondence and similar graphic originals is known as the thermographic copying process. It involves brief irradiation of the original, while in heat-conductive association with the copy-sheet, with high-intensity infra-red radiation. Image areas of the copy-sheet corresponding to the thus preferentially heated radiation-absorptive inked areas of the original are visibly changed. Background areas remain unchanged and still visibly heat-sensitive. For originals having infra-red absorbing characters on both sides, it is necessary to utilize the front-printing process requiring the use of a copy-sheet that is highly transmissive of infra-red radiation and that is therefore ordinarily quite thin. These. thin copy-sheets are highly flexible and in some cases have been yfound difficult to handle, assemble, and tile. Therefore, it has been found desirable to laminate to the copy-sheet back side a back-up sheet comprising heavy paper coated with a heat-activatible adhesive. The copy-sheet thus reinforced has the desirable handling and filing characteristics of heavy bond paper.

The lamination process is performed by again passing the thermographically imaged copy-sheet through the thermographic copying machine with the adhesive-coated back-up sheet placed in heat-conductive contact therewith. It is convenient to utilize the identical thermographic copying machine both for copying and for laminating. In many cases, however, neither the copy-sheet nor the back-up sheet are sufficiently radiation-absorptive to produce fully effective heating of the composite with the radiant energy available. In other cases the image areas of the copy are so highly absorptive of radiation as to become excessively heated when thus irradiated, so that the still heat-sensitive background area immediately adjacent to the image characters undergoes visible change, resulting in a thickened or blurred image. Often times the characters become so thickened and deformed as to be rendered completely indiscernible.

The present invention provides for the highly eflicient use of the intense radiant energy available from conventional thermographic copying machines during lamination, while preventing image thickening or blurring in the copy. These objects are attained by providing a radiationeabsorptive adapter or carrier in which the composite of imaged copy-sheet and back-up sheet are placed during passage through such machine. The adapter eiiiciently and nniformly absorbs the radiation and is uniformly heated thereby. The heat is conducted to the composite whereby the adhesive is activated to laminate the two sheets together under the pressure supplied by the machine. The carrier transmits the laminating pressure smoothly and uniformly `over the entire sheet area. Heating is con trolled so that the temperature at no point exceeds the conversion temperature of the copy-sheet, so that blurring or thickening of the image characters or visible change in the background areas is avoided.

In the appended drawing:

FIGURE 1 represents in plan view one form of carrier or adapter `of the invention with the cover member thereof partially cut away to show a portion of a dual-sheet composite thereunder in position for heat-lamination; and

FIGURE 2 represents, in edge-elevation, section 2-2 of the structure of FIGURE 1.

The unitary carrier l@ consists of a soft, resiliently Compressible but dimensionally stable, flexible base 1l, an outer cover I3, and an inner radiation-absorptive sheet material i6. The latter two components are joined together at the trailing edge of the carrier, as by the sewn seam 18, whereas all three components are joined together near the leading edge of the carrier, as by the sewn seam l2.

The composite of thermoplastic adhesive backup sheet l5 and imaged copy-sheet 14 is placed within the carrier as illustrated and the whole is then subjected to brief intense irradiation, e.g. by passing it through a Thermo- Fax brand Secretary thermographic copying machine. The uniform heating effect produced on absorption of the radiant energy in the sheet I6 and conserved by the insulating effect of the outer cover 13 and the base 11 is sufcient to activate the thermoplastic adhesive of the backup sheet l5. The compression provided by the copy-machine is smoothly and uniformly transmitted to the composite by the resiliently compressible base I1 having tloc surface 19. The backup sheet is thereby smoothly and firmly adherently bonded to the copysheet M.

Although similar procedures may he followed, and similar results obtained, with separate base, cover, and absorption sheets, the unitary carrier just described permits much more rapid and uniform operation.

Typical carrier structure will now be further described in terms of specific illustrative but non-limiting Examples.

Example 1 Twenty-tive parts of thermosetting polyester urethane resinous adhesive having a decomposition temperature of approximately 400 F. is dissolved into 75 parts of ethyl Cellosolve (ethylene glycol monoethyl ether). This solution is coated onto 3mil Mylar polyester fihn to a wet coating weight of approximately 192 grains per square foot (12.5 grams/sq. ft). Whilel the coating is still wet, 30 mesh cotton floc is electrostatically deposited thereon to a density of 60` grains per square foot (4 grams/sq. ft). The coating is heated for approximately one-half hour at 250 F. to provide a iiexible sheet material having a resilient, cured surface coating. The sheet material is cut into sections of desired size, typically having the dimensions of 81/2" by 13 to provide a base member.

Thirty pound basis weight carbonloaded paper, containing approximately cnequarter its weight of carbon black and about 4% of a butadiene-styrene copolymer serving as a polymeric binder, is cut into a sheet the dimensions of which are 81/2" by l2". Fifty-mesh cotton gauze sheeting is then cut into a sheet the dimensions of which are also 81/2" by l2". A cover member is formed by conterminously superimposing the gauze sheeting component over the carbon-loaded paper component and sewing them together along one 81/2 edge. The cover member, paper side downward, is conterminously super-imposed upon the floc side of the base member and sewn thereto along the exposed l margin of the base member, thereby completing the carrier or adapter. Although it is not essential that the cover member be so positioned a. finite distance away from one extremity of the base member, the adapter is more easily introduced betwen the rollers of a thermographic copying machine when such is the case.

The coated side of a Lfront-printed thermographic copy-sheet having infra-red absorbing graphic characters and background areas visibly heat-sensitive at 120 C. is placed against the coated side of a back-up sheet having a resinous thermoplastic coating. These two sheets are placed in the adapter with the back-up7 sheet resting against the base member. The composite is passed through a thermographic copying machine, such as that described in U.S. Patent 2,891,165, and at an energy output sufficient to provide the desired lamination but insufllcient to cause visible change in the copy-sheet. Adequate and uniform lamination of the copy-sheet to the back-up sheet results. Graphic characters are not blurred or even noticeably thickened by the heat-lamination process.

Under the same machine setting but in the absence of the adapter, the image characters become noticeably thickened and blurred. Lamination is marginal and is concentrated at the areas corresponding to the graphic characters. Moreover, when higher energy outputs are utilized to improve lamination, the graphic characters concomitantly become increasingly blurred.

Example 2 An alternate type cover member is formed by utilizing as the outer component l-lb. basis weight machine-glazed paper. The infra-red absorbing inner component consists of 3-mil Mylar tensilized polyester film backing coated with the following dispersion to a dry basis weight of approximately 1 gram per square foot:

50 parts Versarnide 930 resin having a softening point of about 110 C. (Versamide 930 is a product of General Mills Co. and is a condensation product of ethyl diamine and an unsaturated fatty acid.)

50 parts acetylene black 180 parts isopropyl alcohol 50 parts mineral spirits The two sheets are cut to dimensions of 81/2 x 12", and are conterminously sewn together along one 81/2 edge with the coated side of the inner component outward to provide a cover member. With the black coating of the cover member positioned adjacent to the lloc side of the base member, the two members are sewn together as in Example 1. The resultant adapter is operable at a speed approximately 10% faster than the adapter of Example 1.

Example 3 Another type cover member is formed by utilizing as the outer component 10-pound basis weight non-woven hemp sheeting having a l-mil caliper. The infra-red absorbing component consists of -mil .aluminum sheeting coated with the infra-red absorbing carbon dispersion of Example 2 to a dry weight basis of approximately 1 gram per square foot. The hemp sheeting and the carbon coated aluminum sheeting are cut to 81/2 x l2 dimensions, and sewn together with the black coating inward, and then sewn to the base member in the manner described in Examples 1 and 2.

Example 4 A single component cover member can be made utilizing -mil Kel-F fluorinated polymer sheeting coated with the infra-red absorbing carbon dispersion of Example 2 to a dry basis weight of approximately 1 gram per square foot. The cover member is sewn to the base member as described in Examples 1 and 2 with the carbon coating of the cover member adjacent to the floc side of the base member. The resultant adapter etliciently converts infrared radiation to heat similarly to Example 2; the Kel-E sheeting is both highly transrnissive of infra-red radiation and insulates the heat conversion layer adequately to prevent heat loss.

Example 5 Sixty-mill foam rubber sheeting is substituted for the flocked Mylar base member in Examples 1-4. While the excessive thickness of the adapter and copy-sheet combination precludes its use in the moving-belt thermographic copying machine described in U.S. Patent 2,891,165, the resiliency of the rubber sheeting supplies the required degree of pressure-contact when used in conjunction with a moving-lamp thermographic copying machine having a pneumatic cover as described in U.S. Patent 2,740,895.

Example 6 One hundred ten pound basis weight card-stock paper is substituted for the locked Mylar7 base member in Examples 1 4. While the card-stock paper is of comparatively low resiliency it does provide the required degree of pressure-contact when used in conjunction with the moving-belt thermographic copying machine wherein the adapter and copy-sheet combination is pressed between two hard rollers.

Example 7 A cover member is formed by utilizing an infra-red absorbing layer comprising the reaction product of silver behenate and methyl gallate. One hundred grams of silver behenate, 30 grams of the Versamide 930 resin herein described, and 300 grams of isopropyl alcohol are ball milled together for 8-16 hours to provide a uniform dispersion. To grams of the resultant dispersion are added a solution consisting of 25 grams methyl gallate and 40 grams methyl ethyl ketone. This mixture is coated onto 3-mil Mylar tensilized polyester film to a dry basis coating weight of approximately 1 gram per square foot. The web is dried at a temperature of 200 F. so as to cornpletely darken the coating. This coated sheeting is substituted for the infra-red absorbing component in Example 2 with similar results.

What is claimed is as follows:

1. A thin, highly flexible carrier useful in subjecting sheet materials placed therein to a uniform predetermined elevated temperature under exposure to intense infra-red radiation, said .carrier comprising, in order: a ilexible heatinsulative base member for supporting said sheet materials; a flexible, smooth, thin, uniformly highly radiationabsorptive and heat-conductive layer for overlying said sheet materials; and a flexible, radiation-transmissive, heatinsulative outer layer overlying said radiation-absorptive layer.

2. A thin, highly flexible carrier useful in subjecting sheet materials placed therein to a uniform predetermined elevated temperature -by absorption of intense infra-red radiation, said carrier comprising, in order: a lexible, resiliently compressive, heat-insulative base member for supporting said sheet materials; a flexible, smooth, thin, uniformly highly radiation-absorptive and heat-conductive layer for overlying said sheet materials; and a llexible, radiation-transmissive, heat-insulative outer layer overlying said radiation-absorptive layer.

3. A thin, highly flexible carrier useful in subjecting sheet materials placed therein to a uniform predetermined elevated temperature by absorption of intense infra-red radiation, said carrier comprising: a flexible heat-insulative base member; a llexible, radiation-transmissive, heat-insulative outer layer essentially coextensive with said base member and attached to said base member along a common margin; and said carrier including a flexible,

smooth, thin, uniformly highly radiation-absorptive and heat-conductive layer adjacent the inner surface of said outer layer.

References Cited by the Examiner UNITED STATES PATENTS RALPH G. NILSON, Primary Examiner. 

1. A THIN, HIGHLY FLEXIBLE CARRIER USEFUL IN SUBJECTING SHEET MATERIALS PLACED THEREIN TO A UNIFORM PREDETERMINED ELEVATED TEMPERATURE UNDER EXPOSURE TO INTENSE INFRA-RED RADIATION, SAID CARRIER COMPRISING, IN ORDER: A FLEXIBLE HEATINSULATIVE BASE MEMBER FOR SUPPORTING SAID SHEET MATERIALS; A FLEXIBLE, SMOOTH, THIN, UNIFORMLY HIGHLY RADIATIONABSORPTIVE AND HEAT-CONDUCTIVE LAYER FOR OVERLYING SAID SHEET MATERIALS; AND A FLEXIBLE, RADIATION TRANSMISSIVE, HEATINSULATIVE OUTER LAYER OVERLYING SAID RADIATION-ABSORPTIVE LAYER. 